Mine got terribly sick the few times they tried bully sticks, so for them, it was never again.
They really like the Himalayan cheese chew sticks though. They're hard, but long lasting, and don't make a mess!
Casie loves her Nylabone. I only let her chew on it when I'm around though. She's a tough chewer and can get to the point where she's eating plastic. Usually, she focuses on one side of the bone. So, I found a way to make them last longer by using a small rag/cloth and wrapping the chewed up side with a knot so that she'd chew on the other side.
Actually, I only let them chew on stuff when I'm around. When I'm away, they only get the stuffed animals meant for dogs.